There will only be a number of valid instances of a given event equal to the ‘Max Playbacks’ property for that event set in FMOD Designer. The purpose of this feature is to give you control over maximum number of active instances of each event to control memory and CPU usage.

The other property related to this is ‘Max Playback Behaviour’. Let ‘n’ be the max playbacks value, ‘Max playbacks behaviour’ determines what happens when you call getEvent the (n+1)th time.